1. Field of the Invention
The present invention relates in general to door lock devices, and more particularly to door lock devices of a type which generally comprises a latch plate operatively held by a structural base body, and an apertured cover plate attached to the body having the latch plate exposed through the aperture thereof, so that when a striker is led into the aperture, the striker is caught or latched by the latch plate.
2. Description of the Prior Art
Hitherto, various door lock devices have been proposed and put into practical use particularly in the field of motor vehicles. Widely used are of a type which comprises a latch plate operatively held by a structural base body secured to a door, and an apertured cover plate attached to the body in a manner to expose the latch plate through the aperture thereof, so that when a striker secured to a vehicle body is led into the aperture, the striker is caught or latched by the latch plate. For reinforcing the structural base body, the cover plate is usually constructed of steel plate.
Some of the cover plates used in such conventional door lock devices are shaped flat and have a generally U-shaped structure (or horse shoe structure) for defining the aperture therein.
However, due to the flat and U-shaped structure of the cover plate, the flexural strength of the same in the direction to cross the aperture is poor. This means that the mechanical strength fo the structural base body to which such cover plate is secured is also poor. Thus, when an abnormally large impact force is applied to the lock device by the striker due to sudden closing of the door or the like, it tends to occur that the structural base body of the lock device is damaged. Although increasing the thickness of the structure base body may solve such drawback, the increase in thickness induces a bulky and heavy construction of the door lock device.